- Tuning the regioselectivity of (benzimidazolylmethyl)amine palladium(II) complexes in the methoxycarbonylation of hexenes and octenes
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Reactions of N-(1H-benzoimidazol-2-ylmethyl-2-methoxy)aniline (L1) and N-(1H-benzoimidazol-2-ylmethyl-2-bromo)aniline (L2) with p-TsOH, Pd(AOc)2 and two equivalents of PPh3 or PCy3 produced the corresponding palladium comp
- Tshabalala, Thandeka A.,Ojwach, Stephen O.
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p. 339 - 346
(2018/03/21)
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- Palladium-Catalyzed Carbonylation of sec- and tert-Alcohols
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A general palladium-catalyzed synthesis of linear esters directly from sec- and tert-alcohols is described. Compared to the classic Koch–Haaf reaction, which leads to branched products, this new transformation gives the corresponding linear esters in high yields and selectivity. Key for this protocol is the use of an advanced palladium catalyst system with L2 (pytbpx) as the ligand. A variety of aliphatic and benzylic alcohols can be directly used and the catalyst efficiency for the benchmark reaction is outstanding (turnover number up to 89 000).
- Dong, Kaiwu,Sang, Rui,Liu, Jie,Razzaq, Rauf,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 6203 - 6207
(2017/05/22)
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- First examples of the selective carbonylation of C6-C10 linear alkanes to tertiary carbonyl-containing compounds
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The carbonylation of C6-C10 n-alkanes with CO in the presence of CBr4·2A1Br3 at -40°C and 1 atm CO leads to the products of non-destructive carbonylation, i.e., the esters of tertiary carboxylic acids, R1/
- Akhrem, Irena S.,Afanas'eva, Lyudmila V.,Vitt, Sergei V.,Petrovskii, Pavel V.
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p. 180 - 182
(2007/10/03)
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- Dirhodium(II) tetrakis(perfluoroalkylbenzoates) as partially recyclable catalysts for carbene transfer reactions with diazoacetates
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Three highly fluorinated dirhodium(II) tetrakis(benzoates), [Rh2(O2CRF)4, RF=C6H4-4-C6F13 (3) and C6H3-3,5-di(CnF2n+1) (n=6: 4; n=8: 5)], have been prepared and characterized. Only 4 and 5 are suited for applications in fluorous synthesis due to their excellent solubility in fluorous solvents. They were found to catalyze the following carbenoid reactions of diazo compounds in the fluorous solvents 1,1,2-trichloro-1,2,2-trifluoroethane and perfluoro(methylcyclohexane): cyclopropanation of styrenes using methyl diazoacetate, intermolecular carbene C-H insertion into hexane with methyl diazoacetate, and intramolecular aromatic C-H insertion of an α-diazo-β-ketoester. Except for the second reaction type, the catalyst could be recovered to a high extent by a liquid-liquid extraction (fluorous solvent - dichloromethane) due to its preference for the fluorous solvent. For the cyclopropanation reactions, the recovered catalyst was used in four subsequent reaction/workup cycles without significant loss of activity. In contrast, the catalyst could not be recovered from the carbenoid C-H insertion reaction with hexane; apparently, some by-products of this sluggish reaction, such as carbene dimers and oligomers, caused the deactivation or destruction of the catalyst.
- Endres, Andreas,Maas, Gerhard
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p. 3999 - 4005
(2007/10/03)
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- Deamination Reactions, 44. Decomposition of 1-Alkylcyclopropanediazonium Ions
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1-Methyl- (17), 1,2-dimethyl- (41, 44), 1-propyl- (64), 1-(1-methylethyl)cyclopropanediazonium ions (80), and -1-diazonium ions (93) have been generated by alkaline cleavage of the analogous nitrosocarbamates in methanol.Cyclopropyl-allyl transformation and nucleophilic displacement were the only reactions of 17, 41, 44, and 93 while elimination and 1,2-shifts of an α-hydrogen compete increasingly with 64 and 80.The stereochemistry of ring cleavage and nucleophilic displacement has been explored, using 2-D labels in the case of 17 and 93.Cyclopropanediazonium ions (1) and 41 react stereospecifically, 17 and 44 are moderately stereoselective (ca. 85:15), and 93 is entirely unselective.The data indicate a gradual changeover from concerted to stepwise mechanisms.Appreciable stabilization of the positive charge is required to reach the SN1 extreme.
- Kirmse, Wolfgang,Rode, Jutta,Rode, Klaus
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p. 3672 - 3693
(2007/10/02)
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